Townend ring

File:Armstrong Whitworth AW.154 Argosy with townend ring L'Aéronautique July,1929.jpg

The Townend ring was the invention of Dr. Hubert Townend of the British National Physical Laboratory[http://v3.espacenet.com/publicationDetails/originalDocument?CC=GB&NR=320131A&KC=A&FT=D&date=19291010&DB=EPODOC&locale=en_gb Patent Specification 320131: Improvements in or relating to aircraft], 8 July 1933 (amended specification from original dated 10 July 1928). in 1929. Patents were supported by Boulton & Paul Ltd in 1929.[https://wayback.archive-it.org/all/20110827041209/http://brevets-patents.ic.gc.ca/opic-cipo/cpd/eng/patent/304755/summary.html#view_or_download_imagesOriginal 1930 Canadian patent CA 304755 by Hubert Townend with drawings].{{cite web | url=https://patents.google.com/patent/US1813645 | title=Means for reducing eddy formation in the airflow passing aircraft bodies }} In the United States it was often called a "drag ring". It caused a reduction in the drag of radial engines and was widely used in high-speed designs of 1930–1935, before the long-chord NACA cowling came into general use. Despite suggestions of it exploiting the Meredith effect, low airspeeds, low temperature differences and small mass flows make that unlikely,"A History of Aircraft Piston Engines" by Herschel Smith, (Sunflower University Press Manhattan, Kansas, 1981, {{ISBN|0-89745-079-5}}), 255 pp. particularly when combined with the lack of flow control as the air exits the cowling.Becker, J.; The high-speed frontier: Case histories of four NACA programs, 1920–1950, SP-445, NASA (1980), [http://www.hq.nasa.gov/pao/History/SP-445/ch5-5.htm Chapter 5: High-speed Cowlings, Air Inlets and Outlets, and Internal-Flow Systems: The ramjet investigation].

Although superior to earlier cowlings, and uncowled engines in terms of drag and cooling, above {{convert|217|kn|km/h mph|abbr=on}} the NACA cowling was more efficient and soon replaced it in general use.{{cite web |url=https://history.nasa.gov/SP-4219/Chapter1.html |title=Engineering Science and the Development of the NACA Low-Drag Engine Cowling |author=Hansen, James R. |work=From Engineering Science to Big Science: The NACA and NASA Collier Trophy Research Project Winners |access-date=2007-04-28 |archive-url=https://web.archive.org/web/20041031054823/https://history.nasa.gov/SP-4219/Chapter1.html |archive-date=2004-10-31}}{{failed verification|date=August 2014}}

File:Bundesarchiv Bild 101I-026-0122-32A, Griechenland, Kreta, Ju 52.jpg Ju 52/3m being serviced in Crete in 1943: Note the narrow-chord Townend ring on the central engine and the deeper-chord NACA cowlings on the wing engines.]]

Examples of aircraft with Townend rings include the Boeing P-26 Peashooter, the Vickers Wellesley, the Fokker D.XVI and the central engine on the Junkers Ju 52/3m.{{efn-lr|The wing engines of the Ju 52 had longer NACA cowlings, but the central engine only had space for the shorter Townend ring.}}

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{{Commons category|Townend rings}}

• [https://web.archive.org/web/20070319035020/http://www.aeroplanemonthly.com/glossary/T_news_70050.html The Spotters Glossary]
• {{citation |journal=The Aircraft Engineer (Supplement to Flight) |url=http://www.flightglobal.com/pdfarchive/view/1934/1934%20-%200133.html |title=Engine Cowling: With Special Reference to the Air-cooled Engine |last=North |first=J. D. |date=8 February 1934 |pages=133–137 |id=No. 1311 |volume=XXIV |number=6}}
• {{citation |journal=The Aircraft Engineer (Supplement to Flight) |url=http://www.flightglobal.com/pdfarchive/view/1934/1934%20-%201397.html |title=Engine Cowling |last=North |first=J. D. |date=22 February 1934 |pages=174a–174f |id=No. 97 |volume=IX |number=2}}
• {{citation |journal=Flight |url=http://www.flightglobal.com/pdfarchive/view/1934/1934%20-%200157.html |title=Engine Cowling |date=15 February 1934 |id=No. 1312 |volume=XXVI |number=7 |pages=157–158}}

{{Aircraft components}}

Category:Aircraft propulsion components